Science & Environment

Coronavirus: Cracking the secrets of how bats survive viruses

Greater mouse-eared bat Image copyright Olivier Farcy
Image caption The greater mouse-eared bat catches insects in flight

Scientists have deciphered the genetic blueprints of six of the world's bats.

Their codes of life contain genetic clues to their "exceptional immunity", which protects them against deadly viruses.

Researchers hope to use the information to crack the secrets of how bats carry coronaviruses without getting sick.

They say this may ultimately provide solutions to help human health during this and future pandemics.

Prof Emma Teeling of University College Dublin said the "exquisite" genome sequences they have unravelled suggest bats have "unique immune systems".

And understanding how bats can tolerate viruses without getting sick could help in the development of new treatments for viruses such as Covid-19.

"If we could mimic the immune response of bats to viruses, that allows them to tolerate them, then you could look to nature to find a cure," she told BBC News.

"It's already evolved, we don't need to reinvent the wheel. We now have the tools to be able to understand the steps we need to take; we need to develop the drugs to do it."

Prof Teeling is the co-founder of the Bat1K project, which aims to decode the genomes of all 1,421 living bat species.

"These genomes are the tools needed to identify the genetic solutions evolved in bats that ultimately could be harnessed to alleviate human ageing and disease," she said.

Covid-19 is thought to have arisen in bats, passing to humans through another, as yet unidentified, animal. A number of other diseases, including Sars, Mers and Ebola, are thought to have jumped to humans this way.

Ecologists and conservationists have warned that bats should not be persecuted; when left undisturbed in their natural habitats, they pose little risk to human health.

And they are vital for the balance of nature. Many are pollinators, dispersing the seeds from fruit, and others are insectivores, eating millions of tons of insects a night.

Which bats species were decoded?

Six bat species: the greater horseshoe bat (Rhinolophus ferrumequinum), the Egyptian fruit bat (Rousettus aegyptiacus), the pale spear-nosed bat (Phyllostomus discolor), the greater mouse-eared bat (Myotis myotis), the Kuhl's pipistrelle (Pipistrellus kuhlii) and the velvety free-tailed bat (Molossus molossus).

Image copyright Daniel Whitby
Image caption The greater horseshoe bat is the largest horseshoe bat in Europe

What do the studies reveal?

An international team of researchers used cutting edge technologies to sequence the bats' genome and identify the genes present.

By comparing the blueprint of the bat against 42 other mammals they were able to find out where bats are located within the tree of life.

Bats appear most closely related to a group that consists of carnivores (dogs, cats and seals, among other species), pangolins, whales and ungulates (hooved mammals).

A trawl of genetic differences identified regions of the genome that have evolved differently in bats, which may account for their unique abilities.

The genetic detective work revealed genes that may contribute to echolocation, which bats use to hunt and navigate in complete darkness.

How could the information help fight this and future pandemics?

The work has implications for human health and disease, by revealing a large number of genetic changes that give bats protection from viruses.

The researchers think knowledge of bat genomes could help explain how the flying mammals tolerate coronavirus infections, which may, in the future, help in fighting pandemics.

"These changes may contribute to bats' exceptional immunity and points to their tolerance of coronaviruses," said Dr Michael Hiller of the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden, Germany.

In many viral infections, it is not the virus itself that leads to death, but the acute inflammatory response brought on by the body's immune system.

Bats can control this. So, while they may be infected, they do not show visible signs of disease.

The research is published in the journal Nature.

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